Groves increasingly are abandoned by financially stretched owners no longer able to care for the citrus trees. Other groves, snapped up in boom times by speculators planning a quick flip, are ignored now that buyers see there's no development heading their way.

The result? Across Florida's citrus belt, 138,516 acres of groves lie officially abandoned. That's up more than 6 percent from 2008.

A grove is considered abandoned when it has not been cared for nor produced a commercial harvest within the past two years, says the U.S. Department of Agriculture.

The greater Tampa Bay area, stretching from Citrus County in the north to Polk County in the east to Manatee County to the south, accounts for more than 22,600 acres of abandoned citrus groves. Abandonment is most acute in citrus-heavy counties such as Polk (10,791 acres abandoned) and, No. 1 statewide, St. Lucie County (27,321 acres abandoned) on Florida's east coast.

Suburban Pinellas County, which has slowly watched its modest citrus industry be replaced by sprawl and development, is one of the smallest counties still producing citrus. Pinellas and Alachua County are least affected by abandoned citrus groves.

Just as acres of abandoned groves are slowly increasing, land devoted to growing citrus in Florida continues to shrink. In 1972, Florida boasted just under 660,000 acres devoted to oranges and just over 878,000 to all citrus crops.

In 2010, the numbers are far smaller: 483,418 acres for orange crops and 554,037 for all citrus.

The decline can be blamed on encroaching development, land costs, foreign competition and — let's come full circle — increasing numbers of abandoned citrus groves.

The citrus industry hates abandoned groves because they often become havens for disease. If no one is paying attention to the citrus trees — spraying them to fight bugs or burning them when they cannot be salvaged — they can fall vulnerable to citrus canker and, much more onerous these days, citrus greening.

In the worst-case scenario, an active citrus grove finds itself adjacent and vulnerable to a diseased grove.

Both canker and greening (also known as yellow dragon disease) hurt citrus but have different effects. Citrus canker mars the look of citrus. So while any affected fruit cannot be sold as fresh fruit, it can be used to produce juice. But citrus greening, caused by tiny lice known as the Asian citrus cyllid, produces shriveled and bitter tasting fruit. It cannot be used for anything.

In Florida, 95 percent of the orange crop is processed to produce juice. That's why the citrus industry is more panicked over the spread of greening than canker.

Efforts against these diseases exist but are limited by the lack of cures.

"Because of the cyllid and threat of citrus greening, we need to get abandoned groves cleaned up," says Mike Fagan, a Florida Department of Agriculture spokesman.

Think of it like the Middle Ages, terrorized by the plague. As recessionary ripples go, this one's nasty.